The present invention relates to a method of and an apparatus for recording a color image, and more particularly to a method of and an apparatus for recording a color image on the basis of a color video signal which is used in information processing apparatuses such as a computer, a word processor and a color image reader.
In a color image recording apparatus for recording a color image which is used in information processing apparatuses such as a computer, a word processor and a color image reader, by utilizing electrophotographic techniques, a plurality of toner images of of different colors are formed on a primary recording medium independently of each other, and these toner images are then transferred to a secondary recording medium so that the toner images overlap each other, to form a color image on the secondary recording medium.
In a general apparatus for recording an image by utilizing electrophotographic techniques, the surface of a photoconductive, light-sensitive drum is uniformly charged with, the charged surface of the drum is exposed to light in accordance with a video signal to form an electrostatic latent image, the latent image is developed to form a toner image, and the toner image is transferred to recording paper. In order to record a color image in the above-mentioned manner, the surface of the photoconductive, light-sensitive drum is uniformly charged with electricity, the electrified surface of the drum is exposed to light in accordance with a video signal which produces a first color, to form an electrostatic latent image, the latent image is developed by a developing device for the first color, to form a toner image of the first color, and the toner image is transferred to recording paper. Then, the surface of the drum is again charged uniformly with electricity, the electrified surface of the drum is exposed to light in accordance with a video signal which produces a second color, to form an electrostatic latent image, the latent image is developed by a developing device for the second color, to form a toner image of the second color, and the toner image of the second color is transferred to the recording paper so that the toner image of the first color and the toner image of the second color overlap each other on the recording paper. A toner image of a third color can be formed and transferred in the above-mentioned manner, if necessary.
In order to expose the surface of the photoconductive, light-sensitive drum to light in accordance with a video signal used in an information processor, a laser beam emitted from a semiconductor laser which is turned on and off in accordance with the video signal, is usually incident on the surface of the drum.
In such a color image recording apparatus, there arises the following problem. That is, it is very difficult to form toner images which have different colors and are to be transferred to a sheet of recording paper, on the surface of a photoconductive, light-sensitive drum so that the toner images are accurately located in relation to each other. In more detail, it is very difficult to rotate the photoconductive, light-sensitive drum uniformly. Hence, it is difficult to accurately locate a second toner image on the surface of the drum in relation to a first toner image on the surface of the drum. Thus, the toner images deviate from each other in the rotational direction of the drum. When two contiguous toner images of different colors on the recording paper are deviated from each so that the toner images are separated, a white gap (that is, a gap having the base color of the recording paper) is generated in the running direction of the recording paper. Thus, the picture quality of the toner images transferred to the recording paper is deteriorated.
A color image recording apparatus of this kind is described in the 1989-5-15 issue of a Japanese publication "Nikkei Mechanical".